SOMERVILLE, N.J. – Debris, gunk and worn-down parts in the firing mechanism meant that Jayson Williams’ “shotgun was basically an accident waiting to happen,” a gun expert said at the ex-NBA star’s manslaughter trial yesterday.

“It is my opinion that this particular shotgun is capable of discharging in several ways other than by a conscious or volitional pull of the trigger,” testified Richard Ernest in Somerset County court.

Ernest’s findings about the Browning Citori gun boosted defense claims that a weapon misfired, killing limo driver “Gus” Christofi on Feb. 14, 2002 without Williams doing anything reckless. The expert’s tests on a similar gun showed that wood chips in the firing mechanism could have caused a misfire without a trigger pull.